Brian Kernighan count
Implement a function that counts set bits using Brian Kernighan's efficient algorithm.
Reverse Bits
Implement a function that reverses the bits of a given 32-bit unsigned integer.
Swap Odd and Even Bits
Write a function that swaps odd and even bits of a non-negative integer.
Clear Rightmost Set Bit
Write a function clear_rightmost_set_bit that accepts a non-negative integer and returns the integer with its rightmost set bit cleared.
Maximum XOR Pair
Implement max_xor_pair(nums) that returns the maximum XOR value obtainable by pairing any two numbers in the given list.
Find Duplicate Bits
Given a positive integer, return the positions where the bit value appears more than once in its binary form.
Toggle kth Bit
Implement a function that toggles the kth bit of a non-negative integer (0-indexed from the least significant bit) and returns the new integer.
Odd Parity Bit
Given an integer, return the odd parity bit (0 or 1) so that total number of 1-bits in the 8-bit representation becomes odd.
Parse bit field flags
Write a function that unpacks a bit field integer into a dict of named boolean flags.
Subset XOR sum
Given a list of integers, compute the bitwise XOR of each non-empty subset and return the sum of those XOR totals.
Check kth bit
Implement a function that checks whether the k-th bit of a non-negative integer is set (1) or not (0).
Even Parity Bit
Given an integer, return the even parity bit (0 or 1) that makes the total count of set bits even.
Find in Mountain Array
Implement a function to search for a target value in a mountain array using binary search.
Flipping an Image
Implement a function that flips an image represented as a binary matrix by reversing each row and inverting each pixel.
Encode Base64 String
Write a function that encodes a UTF-8 string into a base64 string without using the base64 module.
Base64 Encode Decode
Implement Base64 encoding and decoding functions that handle padding and all standard characters.
XOR Cipher Encode
Implement the XOR cipher: encode a string by XORing each character with a key character.
Showing 25–41 of 41 challenges
Guide: free Python coding challenges
Practice Python by solving problems
PythonSkillset challenges are hands-on coding exercises from beginner to advanced. Open a challenge, read the problem, write Python in the split-pane editor, and run tests with Pyodide — no install required.
How to use the arena
- Pick a category — basics, algorithms, strings, and more
- Open a challenge, read the statement, and edit the starter code
- Run tests, fix failures, then try a related quiz or tutorial lesson
Challenges vs tutorials and quizzes
Challenges test what you can build under constraints. For guided teaching, use our Python tutorials. For quick checks, try quizzes or copy snippets from code samples.